Man not everyone in this world is struggling for bitcoins.There are some big gamblers,betters too whose pasion is gambling.I still remember one guy who use to bet 50+ bitcoin on his every sport bet on directbet and guess what at 1.03,1.07 such odds.He betted 62 btc once at 1.02 odds..He risked that much bitcoin for such low odds..so yeah there are some people who have that much bitcoin..Now where did they get that much? well they bought it obviously coz it's very difficult to earn such amount..it may take years to earn that much online.
he likes safe bet, like i did on French Open, Wimbledom Open(won 5 btc or more, can't remember now) this year, the results were very good, if i kept betting like that, i would still profit many btc, but i didn't do that again, so i lost a lot of money in the end, you know such low odds will happen in djokovic vs weak players, now those weak players are not able to beat djokovic, so the bet is very safe, even i called it FREE MONEY.
What you replied is not 100% correct i have seen djokovic losing to weak players , so if you are playing like this on low odds for 50 matches also if one match goes wrong your whole bankroll we become zero, so not always all matches go according to the players some time it goes according to the situation.
if you run thatway to bet continuously and i am sure you will get busted one day, so the previous "FREE MONEY" will be mean nothing.
let's say you bet 20 btc @1.01 , you will get 0.2. do it 100 times you will get doubled profit. that estimate happened if in that 100 times there is no unexpexted result. unfortunately gambling are gambling there always something surprising every times.
highrollers always have different thinking due their huge capital amount which affected to gamble decision so let them go mad we loveto see it as a enternainment.